1. Field of the Invention
The invention relates to a lock for a motor vehicle door or hatch according to the combination of features of claim 1.
2. Brief Description of the Related Art
It is known in the art that when a side door is closed and a latch bracket or latch bolt attached to the vehicle body enters the catch of the lock and/or when the latch bracket or latch bolt goes through the various relative orientations with respect to the catch, sounds are produced, which should be avoided for comfort reasons. A variety of solutions are known to reduce the described noise generation.
So it is known, for example, on the one hand to coat the contact areas between the catch and the latch bracket or latch bolt with an elastic damping layer (DE 102 16 313 A1, DE 10 2004 031 266 A1, DE 10 2006 028 423 A1), and on the other hand to provide an additional protective layer on said damping layer, which is not only elastic, but also reduces wear and tear and prevents creaking noises from occurring in the closed position of the lock (DE 10 2006 028 423 A1).
Furthermore, from DE 10 2004 031 266 A1 is known a lock with a catch, which features a lip-like insertion opening for the latch bracket, which is bounded by a support leg and a locking leg. As a result of cooperation between the latch bracket and the support leg, the catch rotates into a closed position, in which a spring-loaded pawl automatically engages with a supporting shoulder of the catch. In the closed position, a spring element tensions the latch bracket against a wall that limits the insertion opening and that is formed by the support leg. The spring element narrows the insertion opening. During the insertion of the locking pin into the insertion opening, the spring element is biased or further biased by the latch bracket.
Moreover, from DE 44 20 185 A1 is known a door lock for a motor vehicle door having a friction brake, comprising a cam at the catch and a leaf spring, which protrudes into the path of movement of the cam shortly before the closed position is reached in order to slow down the pivoting movements of the catch and, accordingly, to avoid operational noises.
Furthermore, from DE 38 25 594 A1 is known a lock for motor vehicle doors or hatches, including a catch cooperating with a vehicle-mounted latch, wherein the catch includes a receiving conduit adapted to receive the latch. To avoid any mutual backlash between the catch and the latch, a leaf-like guide spring is attached at both of its ends to a portion of the catch that lies opposite the front side of the latch in a closed position. The guide spring enters the lower portion of the cross-section of the receiving conduit such that the front side of the latch glides along the guide spring while being acted upon by it.
Additionally, from DE 103 20 457 A1 is known a motor vehicle door lock with a catch, a pawl, and a latch bolt that enters an inlet opening and cooperates with the catch, wherein the inlet opening features at least a damping element made of thermoplastic material for the latch bolt with a stop leg for the latch bolt and a cushioning leg for the catch. A spring lip may be integrally molded on the stop leg.
Finally, DE 20 2008 012 010 U1 discloses a spring-loaded limiter for a latch bracket or latch bolt for a motor vehicle lock, which is primarily described as a locking part. Said spring-loaded limiter is formed by a torsion spring. A spring arm of the torsion spring supports a plastic spring tongue formed as a single part with the lock housing. In the closed position, the spring tongue is received while being pretensioned at one side by a receiving portion of the locking part and is received at the other side by an arm of the catch.
Although such a conventional lock certainly ensures sufficient noise attenuation when the door or hatch is shut, when the motor vehicle is in motion, creaking noises cannot be eliminated as they arise in the closed position of the lock due to the relative motion of the lock housing or the catch with respect to the latch bracket or latch bolt, or due to the preferred choice of materials. Specifically, the spring tongue is made of plastic, as mentioned above, whereas the locking bracket or locking bolt is made of metal, especially steel. Such a pairing of materials causes creaking noises, associated with the stick-slip effect, due to unavoidable accumulation of dirt, and especially due to the corresponding frictional surfaces becoming covered with dust. The invention described below was made in this context.